Among the technologies that allow computers and/or other network devices to form a local area network (LAN), Ethernet has become the dominant networking technology and is standardized in the IEEE 802.3 family of standards. The Ethernet standard has evolved over time so that different variants of the Ethernet protocol now exist to support higher bandwidth, improved media access controls, different physical media channels, and/or other functionalities. For example, IEEE 802.3 now has variants covering speeds (or transmission rates) ranging from 10 Mbit/s, 100 Mbit/s, 1 Gbit/s, to 10 Gbit/s and even higher, and has variants that govern physical channels such as coaxial cables, fiber-optics, and unshielded/shielded twisted-pair cables.
One concern associated with Ethernet devices is power consumption. Because of the simultaneous bidirectional (e.g., full duplex) nature of Ethernet communications, transceivers employed in Ethernet devices and/or networks may consume significant power when operating at very high speeds (e.g., 1 Gbit/s or 10 Gbit/s). Thus, if there is little or no data being transmitted over an associated data link, the transceivers may be instructed to enter a low power mode to reduce power consumption. For example, the Energy Efficient Ethernet (EEE), which is described in the IEEE 802.3az standard, employs a low power idle (LPI) signal that may place the transmitter portions of such transceivers into a “sleep” mode when there is no data to be transmitted. Although assertion of the LPI signal may disable the transmitter portions during the sleep mode, the receiver portions of the transceivers typically remain operational, thereby allowing the transceiver to receive data even though the transmitter portions are in sleep mode. The sleep mode may be terminated by de-asserting the LPI signal (or providing a “normal idle” signal) to “wake-up” the transmitter portions of the transceivers, thereby allowing the transceivers to resume data transmissions.
Typically, a newer Ethernet variant is required to operate at slower speeds to provide backwards compatibility with legacy devices and/or with older Ethernet standards. It is common for the transceivers to repeat the data being sent when operating at slower speeds. For example, a transceiver capable of 1 Gbit/s speeds may simply repeat the transmission of data 10 times when operating in a 100 Mbit/s mode, and repeat the transmission of data 100 times when operating in a 10 Mbit/s mode. However, because many variants of the Ethernet standards were developed before the EEE (e.g., IEEE 802.3az) standards were implemented, the LPI signal designed to trigger sleep mode for high-speed transceivers (e.g., capable of 1 Gbit/s) may not work properly when such transceivers are operating at slower speeds (e.g., at 100 Mbit/s). Similarly, the LPI signal may not work properly when such transceivers perform data repetition and/or combination techniques for any other applicable reasons including, for example, combining several channels to create a higher bandwidth, and/or transmitting data using a dedicated 8 bit/10 bit serializer/deserializer (8 B/10 B SerDes).
Accordingly, there is a need to enable LPI signaling for high-speed Ethernet transceivers that operate in legacy modes (e.g., at slower speeds).
Like reference numerals refer to corresponding parts throughout the drawing figures.